Rechargeable battery

ABSTRACT

A rechargeable battery includes: an electrode assembly including a first electrode, a second electrode, a separator between the first and second electrodes, and first and second electrode tabs respectively coupled to the first and second electrodes; a case accommodating the electrode assembly and coupled to the first electrode tab; and a cap assembly sealing an opening in the case. The cap assembly includes: a cap plate covering the opening in the case; and a terminal plate coupled to the cap plate. The terminal plate includes: a flange portion coupled to and electrically insulated from the cap plate; and a tab connecting portion protruding from the flange portion toward the electrode assembly and extending through a terminal opening in the cap plate to be coupled to the second electrode tab. The terminal plate has a flat outer surface, and the tab connecting portion has a flat inner surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/031,710, filed Sep. 24, 2020, which claims priority to and thebenefit of Korean Patent Application No. 10-2020-0012597, filed in theKorean Intellectual Property Office on Feb. 3, 2020, the entire contentof all of which is incorporated herein by reference.

BACKGROUND 1. Field

Aspects of embodiments of the present disclosure relate to arechargeable battery.

2. Description of the Related Art

A rechargeable battery differs from a primary battery in that it isdesigned to be repeatedly charged and discharged, while the latter isnot designed to be recharged. A low-capacity rechargeable battery may beused in a portable electronic device, such as a mobile phone, a laptopcomputer, and a camcorder, and a large-capacity rechargeable battery maybe used as a power source for driving a motor of a hybrid vehicle andthe like.

Some examples of a rechargeable battery include a nickel-cadmium (Ni—Cd)battery, a nickel-metal hydride (Ni-MH) battery, a lithium (Li) battery,a lithium ion (Li-ion) rechargeable battery, etc. The Li-ionrechargeable battery has an operating voltage that is about three timeshigher than the Ni—Cd battery and the Ni-MH battery and is widely usedas a power supply of portable electronic devices. In addition, thelithium ion rechargeable battery has been widely used because itsrelatively high energy density per unit weight.

As demand for wearable devices, such as a headphone, an earphone, asmart watch, and a body-worn medical device using Bluetooth hasincreased, a need for a rechargeable battery having a relatively highenergy density and an ultra-compact size has been increasing.

An ultra-compact rechargeable battery should have a secure electricalcapacity within a limited size, implement an efficient structure whilereducing weight, and have sufficient structural stability.

The above information disclosed in this Background section is forenhancement of understanding of the background of the presentdisclosure, and therefore, it may contain information that does not formthe prior art that is already known to a person of ordinary skill in theart.

SUMMARY

According to embodiments of the present disclosure, a rechargeablebattery is provided in which both an outer surface and an inner surfaceof a terminal plate are flat.

According to embodiments of the present disclosure, a rechargeablebattery is provided that may structurally prevent (or substantiallyprevent) a short circuit of an electrode tab connected to a terminalplate from a cap plate having a different polarity than the electrodetab.

According to embodiments of the present disclosure, a rechargeablebattery is provided that may improve positional freedom of a pin whenconnecting an external pin (e.g., a connecting member) to a terminalplate of the rechargeable battery.

An embodiment of the present disclosure provides a rechargeable batteryincluding: an electrode assembly including a first electrode, a secondelectrode, a separator between the first electrode and the secondelectrode, a first electrode tab coupled to the first electrode, and asecond electrode tab coupled to the second electrode; a caseaccommodating the electrode assembly and coupled to the first electrodetab; and a cap assembly sealing an opening in the case. The cap assemblyincludes: a cap plate coupled to the case and covering the opening inthe case; and a terminal plate coupled to the cap plate. The terminalplate includes: a flange portion coupled to and electrically insulatedfrom the cap plate; and a tab connecting portion protruding from theflange portion toward the electrode assembly and extending through aterminal opening in the cap plate. The tab connecting portion is coupledto the second electrode tab. Outer surfaces of the flange portion andthe tab connecting portion form a flat outer surface of the terminalplate, and the tab connecting portion has a flat inner surface thatprotrudes into the case.

The flange portion of the terminal plate may be parallel to the capplate.

A first end of the electrode assembly may face the case, a second end ofthe electrode assembly may face the cap plate, and a height differentmay be formed between the inner surface of the tab connecting portionand an inner surface of the cap plate.

The inner surface of the tab connecting portion may be nearer to thesecond end of the electrode assembly than the inner surface of the capplate is.

When the second end of the electrode assembly is a flat referencesurface: a first height may be formed between the inner surface of thecap plate and the second end of the electrode assembly; a second heightmay be formed between the inner surface of the tab connecting portionand the second end of the electrode assembly; and the second height maybe smaller than the first height.

A distal portion of the inner surface of the tab connecting portion thatfaces the second electrode tab may be nearer to the second end of theelectrode assembly than the inner surface of the cap plate is.

When the second end of the electrode assembly is a flat referencesurface: a first height may be formed between the inner surface of thecap plate and the second end of the electrode assembly; a second heightmay be formed between a distal portion of the inner surface of the tabconnecting portion that faces the second electrode tab and the secondend of the electrode assembly; and the second height may be smaller thanthe first height.

The terminal plate may include forged aluminum.

The rechargeable battery may further include an insulating memberbetween the cap plate and the second electrode tab.

The insulating member may have a plate shape with a through openingtherein, and the through opening in the insulating member may correspondto the terminal opening in the cap plate.

The through opening in the insulating member may have a smaller diameterthan the terminal opening in the cap plate, and the through opening inthe insulating member and the terminal opening in the cap plate may beconcentric.

When the opening in the case is sealed and closed by the cap assembly, aheight may be a distance between the case and the outer surface of theterminal plate, a diameter may be an outer diameter of the case, and aheight-to-diameter ratio may be 1 or less.

The electrode assembly may be formed by winding the first electrode, thesecond electrode, and the separator interposed between the firstelectrode and the second electrode into a jelly roll shape.

As described above, according to embodiments of the present disclosure,the terminal plate includes a flange portion and a tab connectingportion that together form a planar outer surface, and the tabconnecting portion protrudes into the case with a planar inner surfacein the case. Thus, when connecting an external pin (e.g., a connectingmember) to the terminal plate, the positional freedom of the pin isimproved.

Further, because a height difference is formed between the inner surfaceof the tab connecting portion and the inner surface of the cap plate, ashort circuit between a second electrode tab connected to the tabconnecting portion of the terminal plate and the cap plate, which isconnected to a first electrode and has a different polarity that thesecond electrode tab, may be prevented or substantially prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rechargeable battery according to anembodiment of the present disclosure.

FIG. 2 is an exploded perspective view of the rechargeable battery shownin FIG. 1 .

FIG. 3 is a cross-sectional view taken along the line III-Ill of FIG. 1.

DETAILED DESCRIPTION

The present disclosure will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of thepresent disclosure are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present disclosure.Accordingly, the drawings and description are to be regarded asillustrative in nature and not restrictive.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” or “coupled to” another element or layer, itmay be directly on, connected, or coupled to the other element or layeror one or more intervening elements or layers may also be present. Whenan element or layer is referred to as being “directly on,” “directlyconnected to,” or “directly coupled to” another element or layer, thereare no intervening elements or layers present. For example, when a firstelement is described as being “coupled” or “connected” to a secondelement, the first element may be directly coupled or connected to thesecond element or the first element may be indirectly coupled orconnected to the second element via one or more intervening elements.

In the figures, dimensions of the various elements, layers, etc. may beexaggerated for clarity of illustration. The same reference numeralsdesignate the same elements. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.Further, the use of “may” when describing embodiments of the presentinvention relates to “one or more embodiments of the present invention.”As used herein, the terms “use,” “using,” and “used” may be consideredsynonymous with the terms “utilize,” “utilizing,” and “utilized,”respectively. As used herein, the terms “substantially,” “about,” andsimilar terms are used as terms of approximation and not as terms ofdegree, and are intended to account for the inherent variations inmeasured or calculated values that would be recognized by those ofordinary skill in the art.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, components,regions, layers, and/or sections, these elements, components, regions,layers, and/or sections should not be limited by these terms. Theseterms are used to distinguish one element, component, region, layer, orsection from another element, component, region, layer, or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” or “over” the otherelements or features. Thus, the term “below” may encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations), and the spatiallyrelative descriptors used herein should be interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments of the present invention and is not intended to belimiting of the described example embodiments of the present invention.As used herein, the singular forms “a” and “an” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “includes,”“including,” “comprises,” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

A rechargeable battery according to an embodiment of the presentdisclosure is an ultra-compact battery and may be a coin cell or abutton cell. The coin cell or the button cell is a thin coin-type orbutton-type cell and generally describes a battery having a ratio (H/D)of a height (H) to a diameter (D) (e.g., a height-to-diameter ratio) of1 or less (see, e.g., FIG. 1 ).

Because the coin cell or the button cell is generally cylindrical, ahorizontal cross-section is circular. The present disclosure, however,is not limited thereto, and a horizontal cross-section of therechargeable battery may be oval or polygonal. A diameter may be amaximum diameter (or width) of a case based on a horizontal direction ofthe battery, and a height may be a maximum distance between the case ofthe battery (e.g., a bottom surface of the case) and an outer plane of acap plate.

However, the present disclosure is not limited to the coin cell or thebutton cell, and these are merely example embodiments of the presentdisclosure. A battery, according to embodiments of the presentdisclosure, may be a cylindrical-type or pin-type battery. Hereinafter,an embodiment in which the rechargeable battery is a coin cell or abutton cell will be described in detail as an example.

FIG. 1 is a perspective view of a rechargeable battery according to anembodiment of the present disclosure, FIG. 2 is an exploded perspectiveview of the rechargeable battery shown in FIG. 1 , and FIG. 3 is across-sectional view taken along the line III-Ill of FIG. 1 .

Referring to FIGS. 1 to 3 , a rechargeable battery according to anembodiment includes an electrode assembly 10, a case 20, and a capassembly 30. The cap assembly 30 includes a cap plate 31 and a terminalplate 33. The cap plate 31 and the terminal plate 33 are heat-fused toeach other by a heat-fusion member 34 disposed therebetween.

The heat-fusion member 34 is a medium for mutually coupling the capplate 31 and the terminal plate 33. For example, the heat-fusion member34 may include (or may be made of) an electrically insulating material,such as a polymer, and may be melted by using a laser or the like to befused to the cap plate 31 and the terminal plate 33.

By coupling the terminal plate 33 to the cap plate 31 through theheat-fusion member 34, as shown in the illustrated embodiment, a stablecoupling structure is formed while the terminal plate 33 and the capplate 31 are effectively insulated from each other without using aseparate insulating member.

Because a coin cell is manufactured in an ultra-compact size, it mayhave a design limitation in terms of space, and accordingly, it isdesirable to secure functionality while simplifying a structure and amanufacturing process thereof. In this vein, in the illustratedembodiment, insulation and coupling between the terminal plate 33 andthe cap plate 31 through the heat-fusion member 34 are realized.

The electrode assembly 10 includes a first electrode 11 (e.g., anegative electrode) and a second electrode 12 (e.g., a positiveelectrode) provided at respective sides of a separator 13, which is(e.g., which includes or which is formed of) an electrical insulatingmaterial. The electrode assembly 10 is formed by winding the firstelectrode 11, the separator 13, and the second electrode 12. Therefore,the electrode assembly 10 may be formed as a jelly roll type.

The electrode assembly 10 is configured to charge and discharge acurrent, and a winding shaft (e.g., a winding axis) may be arranged inthe electrode assembly 10 parallel to a height direction of the case 20.A first end (e.g., a lower surface) 101 and a second end (e.g., an uppersurface) 102 of the electrode assembly 10 may be flat and parallel toeach other. In the illustrated embodiment, the electrode assembly 10does not include a center pin, but a center pin may be provided alongthe winding shaft (e.g., at a center of the electrode assembly 10parallel to the winding axis).

The case 20 accommodates the electrode assembly 10 while facing thefirst end 101 from among both ends 101, 102 of the electrode assembly10. As an example, the case 20 has a cylindrical shape that accommodatesthe jelly roll type electrode assembly 10, and the cap assembly 30 sealsan opening 21 in the cylindrical case 20.

The electrode assembly 10 includes a first electrode tab 51 connected tothe first electrode 11 and a second electrode tab 52 connected to thesecond electrode 12, and the first and second electrodes 11 and 12 aredrawn out to the first and second ends 101 and 102 of the electrodeassembly 10, respectively.

When the electrode assembly 10 is accommodated in the case 20, the firstelectrode tab 51 is electrically connected to a bottom of the case 20,and the second electrode tab 52 is electrically connected to theterminal plate 33 of the cap assembly 30.

In addition, the cap plate 31 of the cap assembly 30, while facing thesecond end 102 from among both ends 101, 102 of the electrode assembly10, is coupled to the case 20 to cover the opening 21. The terminalplate 33 is coupled to the second electrode tab 52 while being coupledto the cap plate 31.

Hereinafter, an embodiment in which the first electrode 11 and thesecond electrode 12 are a negative electrode and a positive electrode,respectively, will be exemplarily described, but the present disclosureis not limited thereto. In other embodiments, the first electrode 11 andthe second electrode 12 may be the positive electrode and the negativeelectrode, respectively.

The first electrode (e.g., the negative electrode) 11 is formed in along extending strip shape and has a negative electrode coated portion,which is a region in which a negative electrode active material layer iscoated to a current collector (e.g., a metal foil, such as a Cu foil,current collector), and a negative electrode uncoated portion, which isa region in which an active material is not coated. The negativeelectrode uncoated portion may be disposed at one end portion in alength direction of the negative electrode.

The second electrode (e.g., the positive electrode) 12 is formed in along extending strip shape and has a positive electrode coated portion,which is a region in which a positive electrode active material layer iscoated to a current collector (e.g., a metal foil, such as an Al foil,current collector), and a positive electrode uncoated portion, which isa region in which an active material is not coated. The positiveelectrode uncoated portion may be disposed at one end portion in alength direction of the positive electrode.

The electrode assembly 10 may be inserted into the case 20 through theopening 21, which is formed at one side of the case 20, and the case 20has a space (e.g., has sufficient space) for accommodating the electrodeassembly 10 and an electrolyte therein. For example, the case 20 has acylindrical shape having a height H that is smaller than a diameter Dthereof and has a circular opening 21 so that the cylindrical electrodeassembly 10 may be inserted into an inner space of the case 20.

The terminal plate 33 of the cap assembly 30 includes a flange portion331 and a tab connecting portion 332. The flange portion 331 and the tabconnecting portion 332 form (e.g., together form) a flat outer surfaceon the case 20. The tab connecting portion 332 protrudes into the case20 and has a flat inner surface. The flange portion 331 is formedparallel to the cap plate 31.

Because the terminal plate 33 has a flat outer surface and the innersurface of the tab connecting portion 332 is flat, when an external pin(e.g., a connecting member) is connected to the terminal plate 33 of therechargeable battery, the positional freedom of the pin (e.g., theconnecting member) may be improved.

The flange portion 331 is coupled to the cap plate 31 in an electricallyinsulating state (e.g., the flange portion 331 is coupled to andelectrically insulated from the cap plate 31). The tab connectingportion 332 protrudes from the flange portion 331 toward the electrodeassembly 10 and is inserted into a terminal opening (e.g., a terminalhole) 311 to be connected to the second electrode tab 52 of theelectrode assembly 10.

In the illustrated embodiment, the inner surface 323 of the tabconnecting portion 332 has a height difference ΔH from the inner surface312 of the cap plate 31. Thus, when the second electrode tab 52, whichhas positive polarity, is extended with a length margin between thesecond end 102 of the electrode assembly 10 and the inner surface 312 ofthe cap plate 31, the height difference ΔH provides a safety range (orsafety margin) to prevent (or substantially prevent) a short circuitbetween the second electrode tab 52, which has positive polarity, thecap plate 31, which has negative polarity.

For example, a short circuit between the second electrode tab 52, whichhas positive polarity and is connected to the terminal plate 33, and thecap plate 31, which has negative polarity and is connected to the firstelectrode tab 51, may be structurally prevented (or substantiallyprevented) by the height difference ΔH.

For example, the inner surface 323 of the tab connecting portion 332protrudes farther toward the second end 102 of the electrode assembly 10than the inner surface 312 of the cap plate 31 does, and the innersurface 323 of the tab connecting portion 332 has a flat surface. Whenthe second end 102 of the electrode assembly 10 is a flat referencesurface, a first height H1 is formed between the inner surface 312 ofthe cap plate 31 and the second end 102 of the electrode assembly 10.

Further, a second height H2 is formed between the flat inner surface 323of the tab connecting portion 332 and the second end 102 of theelectrode assembly 10. Because the second end 102 of the electrodeassembly 10 is used as the flat reference surface to measure both thefirst height H1 and the second height H2, the second height H2 issmaller than the first height H1. For example, the height difference ΔHbetween the first height H1 and the second height H2 may structurallyprevent (or substantially prevent) a short circuit between the secondelectrode tab 52 and the cap plate 31.

An insulating member 61 is interposed between the cap plate 31 and thesecond electrode tab 52. In the illustrated embodiment, the insulatingmember 61 has a plate shape corresponding to the cap plate 31, but thepresent disclosure is not limited thereto as long as the insulatingmember 61 is interposed between the cap plate 31 and the secondelectrode tab 52.

The insulating member 61 has a through opening (e.g., a through hole)611 corresponding to the terminal opening 311. The through opening 611may have a smaller diameter than that of the concentric terminal opening311. Therefore, the second electrode tab 52 is further prevented fromshorting to the cap plate 31 through the terminal opening 311.

In addition, an outer (or distal) portion of the inner surface 323 ofthe tab connecting portion 332 facing at least the second electrode tab52 is formed to protrude father toward the second end 102 of theelectrode assembly 10 than the inner surface 312 of the cap plate 31does. Thus, when the second end 102 of the electrode assembly 10 is theflat reference surface, the first height H1 is formed between the innersurface 312 of the cap plate 31 and the second end 102 of the electrodeassembly 10.

The second height H2 is formed between the outer portion of the innersurface 323 of the tab connecting portion 332 facing at least the secondelectrode tab 52 and the second end 102 of the electrode assembly 10.Because the second end 102 of the electrode assembly 10 is the flatreference surface to measure both the first height H1 and the secondheight H2, the second height H2 is smaller than the first height H1. Forexample, the height difference ΔH between the first height H1 and thesecond height H2 may structurally prevent (or substantially prevent) ashort circuit between the second electrode tab 52 and the cap plate 31.

The terminal plate 33 may be formed of forged aluminum. The flangeportion 331 of the terminal plate 33 is formed to be parallel to the capplate 31, the tab connecting portion 332 of the terminal plate 33protrudes into the case 20, and the inner surface 323 of the tabconnecting portion 332 is flat. Thus, the weldability of the innersurface 323 of the tab connecting portion 332 and the second electrodetab 52 may be improved.

Different from stainless steel, aluminum may be forged, and forging isan appropriate processing method that may form the outer surfaces of theflange portion 331 and the tab connecting portion 332 of the terminalplate 33 to be flat and may form the inner surface 323 of the tabconnecting portion 332 of the terminal plate 33 to be flat.

In the illustrated embodiment, the entire inner surface 323, whichincludes the outer portion facing the second electrode tab 52, of theterminal plate 33 may be flat, but in other embodiments, only a portionof the inner surface 323 facing the second electrode tab 52 may beformed flat.

For example, only the outer portion in a diameter direction from amongportions of the inner surface 323 of the tab connecting portion 332facing at least the second electrode tab 52 may be formed to furtherprotrude toward the second end 102 of the electrode assembly 10 than theinner surface 312 of the cap plate 31 does.

In the rechargeable battery according to the illustrated embodiment,when the opening 21 in the case 20 is sealed by the cap assembly 30, theheight H is a distance (e.g., a maximum distance) between the outersurfaces of the case 20 and the terminal plate 33, and the diameter D isan outer diameter (e.g., a maximum diameter) of the case 20. In thisembodiment, a ratio of the height H to the diameter D is 1 or less(H/D≤1). Therefore, the rechargeable battery may have a thin coin orbutton shape, thus, may be considered a coin cell or a button cell.

While the present disclosure has been described in connection with whatis presently considered to be practical embodiments, it is to beunderstood that the present disclosure is not limited to the disclosedembodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims and their equivalents.

<Description of Some Reference Symbols> 10: electrode assembly 11, 12:first and second electrodes 13: separator 20: case 21: opening 30: capassembly 31: cap plate 33: terminal plate 51: first electrode tab 52:second electrode tab 61: insulating member 101: first end 102: secondend 323: inner surface 311: terminal opening 312: inner surface 331:flange portion 332: tab connecting portion 611: through opening D:diameter H: height H1: first height H2: second height ΔH: heightdifference

What is claimed is:
 1. A button cell comprising: an electrode assemblycomprising a first electrode, a second electrode, a separator betweenthe first electrode and the second electrode, a first electrode tabcoupled to the first electrode, and a second electrode tab coupled tothe second electrode; a case accommodating the electrode assembly andcoupled to the first electrode tab; and a cap assembly sealing anopening in the case, the cap assembly comprising: a cap plate coupled tothe case and covering the opening in the case; a terminal plate coupledto the cap plate; and a heat fusion member between the cap plate and theterminal plate, wherein the terminal plate comprises: a flange portioncoupled to and electrically insulated from the cap plate by the heatfusion member arranged therebetween; and a tab connecting portionprotruding from the flange portion toward the electrode assembly andextending through a terminal opening in the cap plate, the tabconnecting portion being coupled to the second electrode tab, andwherein an outer edge of the flange portion is closer to an outer edgeof the cap plate than an outer edge of the heat fusion member in ahorizontal direction of the button cell.
 2. The button cell of claim 1,wherein outer surfaces of the flange portion and the tab connectingportion form a flat outer surface of the terminal plate, and wherein thetab connecting portion has a flat inner surface that protrudes into thecase.
 3. The button cell of claim 2, wherein the flange portion of theterminal plate is parallel to the cap plate.
 4. The button cell of claim2, wherein a first end of the electrode assembly faces the case, and asecond end of the electrode assembly faces the cap plate, and wherein aheight difference is formed between the flat inner surface of the tabconnecting portion and an inner surface of the cap plate.
 5. The buttoncell of claim 4, wherein the flat inner surface of the tab connectingportion is nearer to the second end of the electrode assembly than theinner surface of the cap plate is.
 6. The button cell of claim 4,wherein, when the second end of the electrode assembly is a flatreference surface: a first height is formed between the inner surface ofthe cap plate and the second end of the electrode assembly; a secondheight is formed between the flat inner surface of the tab connectingportion and the second end of the electrode assembly; and the secondheight is smaller than the first height.
 7. The button cell of claim 4,wherein a distal portion of the flat inner surface of the tab connectingportion that faces the second electrode tab is nearer to the second endof the electrode assembly than the inner surface of the cap plate is. 8.The button cell of claim 4, wherein, when the second end of theelectrode assembly is a flat reference surface: a first height is formedbetween the inner surface of the cap plate and the second end of theelectrode assembly; a second height is formed between a distal portionof the flat inner surface of the tab connecting portion that faces thesecond electrode tab and the second end of the electrode assembly; andthe second height is smaller than the first height.
 9. The button cellof claim 1, wherein the terminal plate comprises forged aluminum. 10.The button cell of claim 1, further comprising an insulating memberbetween the cap plate and the second electrode tab.
 11. The button cellof claim 10, wherein an inner edge of the insulating member is closer tothe tab connecting portion than an inner edge of the cap plate in thehorizontal direction of the button cell.
 12. The button cell of claim10, wherein the insulating member has a plate shape with a throughopening therein, and wherein the through opening in the insulatingmember corresponds to the terminal opening in the cap plate.
 13. Thebutton cell of claim 12, wherein the through opening in the insulatingmember has a smaller diameter than the terminal opening in the capplate, and wherein the through opening in the insulating member and theterminal opening in the cap plate are concentric.
 14. The button cell ofclaim 1, wherein, when the opening in the case is sealed and closed bythe cap assembly, a height is a distance between the case and an outersurface of the terminal plate, a diameter is an outer diameter of thecase, and a height-to-diameter ratio is 1 or less.
 15. The button cellof claim 1, wherein the electrode assembly is formed by winding thefirst electrode, the second electrode, and the separator interposedbetween the first electrode and the second electrode into a jelly rollshape.
 16. A button cell comprising: an electrode assembly comprising afirst electrode, a second electrode, a separator between the firstelectrode and the second electrode, a first electrode tab coupled to thefirst electrode, and a second electrode tab coupled to the secondelectrode; a case accommodating the electrode assembly and coupled tothe first electrode tab; a cap assembly sealing an opening in the case,the cap assembly comprising: a cap plate coupled to the case andcovering the opening in the case; and a terminal plate coupled to thecap plate; and an insulating member between the cap plate and the secondelectrode tab, wherein the terminal plate comprises: a flange portioncoupled to and electrically insulated from the cap plate; and a tabconnecting portion protruding from the flange portion toward theelectrode assembly and extending through a terminal opening in the capplate, the tab connecting portion being coupled to the second electrodetab, wherein an inner edge of the insulating member is closer to the tabconnecting portion than an inner edge of the cap plate in a horizontaldirection of the button cell.
 17. The button cell of claim 16, whereinthe insulating member has a plate shape with a through opening therein,and wherein the through opening in the insulating member corresponds tothe terminal opening in the cap plate.
 18. The button cell of claim 17,wherein the inner edge of the insulating member forms the throughopening.
 19. The button cell of claim 17, wherein the inner edge of thecap plate forms the terminal opening.
 20. The button cell of claim 17,wherein the through opening in the insulating member has a smallerdiameter than the terminal opening in the cap plate, and wherein thethrough opening in the insulating member and the terminal opening in thecap plate are concentric.